For about 75 minutes, Seven Psychopaths is a rollicking good movie - kinetic, clever, funny, and brutal. Then, inexplicably, it falls apart. Perhaps writer/director Martin McDonagh (In Bruges) didn't know how to end it, or perhaps his attempts to develop a quasi-dramatic denouement clash so violently with the preceding material that the final half-hour can't satisfy. Whatever the case, Seven Psychopaths falls into the category of entertaining movies undone by disapponting final acts. On balance, one could argue that Seven Psychopaths warrants a better rating than a mediocre **1/2, but the aftertaste is so bitter that it diminishes the sweetness that started off the meal.

There's a "post-Tarantino" vibe to Seven Psychopaths. In the wake of Pulp Fiction's release, there were a lot of copycats - some good, some bad, but all seeking to emulate the rhythms of Tarantino's seminal motion picture. Seven Psychopaths has that feel, although one could argue it arrived to the party about 18 years late. Many of the elements that made Pulp Fiction such a memorable experience are present in Seven Psychopaths, at least during the first 1 1/4 hours: witty dialogue, humor derived from brutality, bursts of violence, and Christopher Walken. There's also some gratuitous nudity and another delightfully nasty performance from the once-squeaky clean Woody Harrelson.

Seven Psychopaths interweaves "reality" with "fantasy" by depicting segments of a screenplay-within-the-screenplay. Marty (Colin Farrell) is an alcoholic, would-be screenwriter who is suffering with a case of writer's block while developing his latest project, a "pacifist" story about psychopaths. His best friend, Billy (Sam Rockwell), offers to help, But Marty is protective of his work. Billy earns a living by kidnapping dogs who are momentarily left unattended by their owners, then returning them and claiming the reward money. He is helped in this scheme by Hans (Christopher Walken), a deeply religious man with a cancer-stricken wife. The seemingly random kidnapping of a Shih Tzu named Bonny puts Billy, Hans, and Marty in danger. Bonny is the beloved pet of gangster Charlie (Woody Harrelson) and he is none-too-pleased about losing his dog. Meanwhile, at large is a serial killer who goes by the name of The Jack of Diamonds and makes his name by killing hit men and murderers.

Seven Psychopaths contains frequent self-referential moments (such as a commentary about how women are treated in Marty's screenplay being representative of how they are presented in the actual movie), some of which are clever and some of which are too obvious. There are a lot of big laughs at unexpected times, not entirely unlike the moment in Pulp Fiction when John Travolta accidentally shoots a guy in the backseat of the car, spraying blood and brains over everything. The disappointment is that all of the wonderful, twisted fun comes to an unexpected end long before the movie is over. The final 30 minutes, with the three main characters camping in the desert, isn't funny or smart and it lacks energy. The showdown is anticlimactic and, although McDonagh tries to do something interesting with it, he doesn't succeed. The subsequent dream sequence and inter-credits scene are equally flat. It's as if the creative juices leaked out around the 2/3 point and seeped into the sandy desertscape.

Seven Psychopaths probably gives us more than seven twisted killers - it's hard to keep track. Is Hans one? Depends. Christopher Walken has some good Christopher Walken moments, including one of the final 30 minutes' few highlights. Sam Rockwell's deadpan, off-kilter humor - a quality beneath which a sense of violence seems to lurk - allows Billy to be unpredictable enough to share the screen with Walken's Hans. Woody Harrelson, in another bad-to-the-bone performance, brings an element of redneck charm to vicious, conscienceless Charlie. Colin Farrell has the unenviable job of playing the "straight man." One reason the final segment of Seven Psychopaths doesn't work is because it focuses on Marty, who's not a lot of fun.

A lot of critics loved McDonagh's previous feature, In Bruges, but my criticism of that movie is the same one I have of this one: an inability to close things out with the same strength evident in the beginning and middle sections. The collapse is more evident in Seven Psychopaths, but the films taken as a set point to an unfortunate trend. The lack of consistency is frustrating and disappointing. Had Seven Psychopaths been able to maintain its initial tone and energy level throughout, it would have been a compelling and memorable experience. As it is, it's an illustration of how it's just as important to have a solid ending as an attention-catching beginning.